package com.example.opengldemo.simple12_02;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import android.opengl.GLES30;

import com.example.opengldemo.util.MatrixState;
import com.example.opengldemo.util.ShaderUtil;

import static com.example.opengldemo.simple12_02.MySurfaceView.UNIT_SIZE;


public class Desert 
{	
	int mProgram;
    int muMVPMatrixHandle;
    int maPositionHandle;
    int maTexCoorHandle;
    String mVertexShader;
    String mFragmentShader;

	FloatBuffer   mVertexBuffer;
	FloatBuffer   mTexCoorBuffer;
    int vCount=0;   
    
    public Desert(MySurfaceView mv,float[] texCoor,int width,int height)
    {    	

    	initVertexData(texCoor,width,height);
    	initShader(mv);
    }

    public void initVertexData(float[] texCoor,int width,int height)
    {
        vCount=6;
        float vertices[]=new float[]
        {
    		-UNIT_SIZE*width,0,-UNIT_SIZE*height,
    		UNIT_SIZE*width,0,-UNIT_SIZE*height,
    		UNIT_SIZE*width,0,UNIT_SIZE*height,
    		
    		-UNIT_SIZE*width,0,-UNIT_SIZE*height,
    		UNIT_SIZE*width,0,UNIT_SIZE*height,
    		-UNIT_SIZE*width,0,UNIT_SIZE*height
        };
        ByteBuffer vbb = ByteBuffer.allocateDirect(vertices.length*4);
        vbb.order(ByteOrder.nativeOrder());
        mVertexBuffer = vbb.asFloatBuffer();
        mVertexBuffer.put(vertices);
        mVertexBuffer.position(0);
        

        ByteBuffer cbb = ByteBuffer.allocateDirect(texCoor.length*4);
        cbb.order(ByteOrder.nativeOrder());
        mTexCoorBuffer = cbb.asFloatBuffer();
        mTexCoorBuffer.put(texCoor);
        mTexCoorBuffer.position(0);
    }
    
    public void initShader(MySurfaceView mv)
    {
        mVertexShader= ShaderUtil.loadFromAssetsFile("simple12_02/vertex.sh", mv.getResources());
        mFragmentShader=ShaderUtil.loadFromAssetsFile("simple12_02/frag.sh", mv.getResources());
        mProgram = ShaderUtil.createProgram(mVertexShader, mFragmentShader);
        maPositionHandle = GLES30.glGetAttribLocation(mProgram, "aPosition");
        maTexCoorHandle= GLES30.glGetAttribLocation(mProgram, "aTexCoor");
        muMVPMatrixHandle = GLES30.glGetUniformLocation(mProgram, "uMVPMatrix");
    }
    
    public void drawSelf(int texId)
    {        

    	 GLES30.glUseProgram(mProgram); 

         GLES30.glUniformMatrix4fv(muMVPMatrixHandle, 1, false, MatrixState.getFinalMatrix(), 0);

         GLES30.glVertexAttribPointer  
         (
         		maPositionHandle,   
         		3, 
         		GLES30.GL_FLOAT, 
         		false,
                3*4,   
                mVertexBuffer
         );       

         GLES30.glVertexAttribPointer  
         (
        		maTexCoorHandle, 
         		2, 
         		GLES30.GL_FLOAT, 
         		false,
                2*4,   
                mTexCoorBuffer
         );   

         GLES30.glEnableVertexAttribArray(maPositionHandle);  
         GLES30.glEnableVertexAttribArray(maTexCoorHandle);  

         GLES30.glActiveTexture(GLES30.GL_TEXTURE0);
         GLES30.glBindTexture(GLES30.GL_TEXTURE_2D, texId);

         GLES30.glDrawArrays(GLES30.GL_TRIANGLES, 0, vCount); 
    }
}